This invention relates to a symmetrical objective for use in the photographic arts field.
Generally lenses intended for use in the photographic arts are required as a condition of their performance to provide a sufficient imaging quality at or near unity magnification and, from a commerical standpoint to provide a field angle as wide as possible with a lens shape as small as possible.
There are advantages and disadvantages in conventional well-known lens systems which may be utilized as wide angle lenses. A symmetrical objective has not been provided which, from a performance standpoint, has little variation in distortion aberration in response to a change in magnification, a small image field of curvature at wide angles of view in which the field angle under a unity magnification is 70.degree. or so, having a good correction of coma flare, and from a structural standpoint having a simple lens configuration, which is small in size and less expensive to produce.